The 180-degree rule
When two people are talking, there's an imaginary line connecting them. As long as the camera doesn't cross it, the viewer understands who's looking at whom. If you cross it by accident, the edit becomes confusing even if every shot is perfect.
The imaginary line
Draw a line between the eyes of two people who are talking: that's the axis of action. Put all your cameras on the same side of that line and A will always look to the right and B to the left. The viewer builds the space without thinking about it.
They share a name because of the 180 degrees (a half turn), but they have nothing to do with each other. This rule is about staging; the other one is about exposure. That's why this one is often called the axis of action rule or simply “the line”.
Shot/reverse shot
The classic way to shoot a dialogue:
- Wide shot or two-shot: establishes both characters.
- Shot of A over B's shoulder (or a close-up of A).
- Reverse shot of B: the same size and angle, from the other side, but on the same side of the axis.
For the two shots to match, keep the same camera height, a similar focal length and the same distance. If A is in a close-up and B in a medium shot, it'll look as if one is more important than the other, which is sometimes exactly what you want.
When you can cross the line
You can jump the line, but you have to take the viewer by the hand:
- With a camera move that crosses it within the same shot.
- When a character moves and redefines the axis.
- With a neutral shot in between: a frontal shot right on the axis, or an extreme close-up.
- On purpose, to disorient: arguments that fall apart, moments of madness.
Continuity between shots
Continuity is the consistency between one shot and the next. Continuity errors are the famous movie goofs: the glass that was full and then half empty, or the shirt whose buttons change.
| Type of continuity | What you need to keep | Example of a mistake |
|---|---|---|
| Props and wardrobe | Same positions, amounts, clothes and hair | The cigarette that grows between shots |
| Eyeline | Eyelines that meet consistently | Two people who seem to be looking the same way |
| Movement and direction | The action continuing in the same direction | Someone exits right and also enters from the right |
| Action | The gesture picking up where it left off | They pick up the mug with their right hand and in the next shot it's in their left |
| Lighting | Same direction, color and intensity | Sunset in one shot and midday in the reverse shot |
Before changing shots, take a photo of the scene with your phone: position of props, clothes, level in the glass. On a film set, the script supervisor does this. On your own projects, that's you.
Screen direction
If a character travels from New York to Chicago and we always show them heading right, the viewer understands the journey. If they suddenly head left, it looks like they're going back. Choose a direction for each journey and stick to it.
- All cameras on the same side of the axis of action.
- Shot and reverse shot with similar height, focal length and distance.
- To cross the line, use a move, a neutral shot, or do it on purpose.
- Watch continuity of props, eyelines, direction and lighting.
Your turn: a real dialogue
Write a six-line dialogue between two people and shoot it with a wide shot, a shot of A and a reverse shot of B.
- First draw a floor plan with the axis and the cameras.
- Edit the dialogue, alternating shots.
- Deliberately shoot a reverse shot that jumps the line and cut it in. Notice the confusion.